


The Great Holy Grail War Body Swap ((Zero Edition))

by Anonymous



Category: Fate/Zero, Fate/stay night & Related Fandoms
Genre: Bodyswap, Child's mind in adult's body, Crack, Crack Treated Seriously, Gender or Sex Swap, Genderbending, Masturbation, Multi, Self-cest
Language: English
Status: In-Progress
Published: 2016-10-06
Updated: 2016-10-06
Packaged: 2018-08-19 20:16:56
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,341
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8223521
Author URL: https://archiveofourown.org/
Summary: Somehow during the 4th Holy Grail War, the bodies of the participants and some of the onlookers are switched around, throwing everything into chaos. Will it be fixed, or will the war become even more of a chaotic hellhole?





	1. Chapter 1

**Author's Note:**

> Happens right after the dock battle, but before Kerry blows up the hotel.

When Gilgamesh opened his eyes, he instantly knew something was different. One as ancient and wise as he was well aware of the state of his body, and his surroundings. Like for one thing he knew he wasn't at the church when he collapsed.....and he also could feel it. An ache in his bones. An ache that shouldn't be there....an ache he hadn't felt since....

Gilgamesh the now former King of Heroes, looked down at his now old wrinkled hands and despaired.  
***  
Tokiomi could feel intense pain. He was in an alley way. How he got here....he couldn't remember but...the pain...the pain was overwhelming him. It felt like a car was ontop of him, crushing him. As he tried to get his bearings, Tokiomi coughed and what came out caused his eyes to go wide. Worms. Worms that looked like.... Tokiomi fell to his knees and put his now shriveled face, in his now equally shiriveled hands.  
***

Irisviel blinked her eyes open. Where was she...last she remembered she was....she couldn't remember. But now she was on a bed. She sat up and instantly felt the difference. No longer did she feel light and limber but...heavy and strong. She looked down and noticed something instantly. Her breasts were missing. Raising an eyebrow in curiosity, Iri stood up and looked further down and caught a peak. While she wasn't modest by any means, she couldn't help but blush at what she saw that was now between her new legs. It was then that she noticed she also...felt different. There was now a power here. A power she didn't have and then...she realized where she had seen these hands and arms before. She was Rider. She was now a heroic spirit. Gasping she looked as she saw the boy who was with him begin to stir. 

"Ah hello are-" Iri began before she was interrupted by the boy jumping into a defensive position. 

"Uh are you uh....you?" Iri asked, sensing the difference in the boy from the brief time she saw him at the docks. He wasn't one to make a defensive position like that...and she recognized that position. It was the position Lancer had when he fought Saber.

"It....appears I am not in the body I am used to." Diarmuid said as he sighed to himself. Tonight was difficult enough...he really didn't need this.

"Iskander you are a most wise king but...how did you instantly know my ailment?" Diarmuid asked the big burly King of Conquerors before him.

"Well...I am not Iskander. I'm Saber's...." Irisviel caught herself. She couldn't give away Kiritsugu's actual role yet.

"Master. Yes I am Saber's master!" She said excitedly, though it sounded silly with her now deep voice.

"Ah forgive me my lady" Diarmuid said, which came out sounding rather...odd in Waver's high pitched voice.

"Lancer...considering what's happened...it seems that we should team up for now." Irisviel proposed, scratching her newfound beard.

"I must agree with your choice of action. We should see if anyone else has been affected and find our bodies. I can only imagine how the boy is doing in mine...." Diarmuid considered.

"Very well then! Onwards Lancer!" Irisviel yelled happily.  
***

When Rin woke up she didn't know where she was. She was just by her mother and now she was in a big mansion and she was much taller. When she tried to walk she felt something there and sat down. This was weird. She was scared as tears formed in her eyes. Where was her mother. Where was she. Would anyone know to look for her? Rin Tohsaka, in the body of Emiya Kiritsugu, began to sob.  
***

"SOLA!" Kayneth cried as he shot up. He was still in the hotel room but then...he fainted!? What a mortifying thing! What would Sola think!? However it was then that he noticed....himself beginning to stir.

"What...what is..." Kayneth's body began to speak and Kayneth gulped. It was then that his body looked at him and screamed.

"WHO ARE YOU! WHAT HAVE YOU DONE!" His body yelled girlishly.

"Sola, it's me.....Kayneth." Kayneth said hesitantly. Everything felt off. There was now a....void where his manhood once was. His chest felt heavy. His hands were now small and dainty. No longer was he wearing his usual pants, but his now shapely legs were covered by form fitting pants, designed to show off his now shapely legs. Kayneth gulped. He was ruined.  
***

Aoi began to stir awake. Had she somehow fallen asleep? The modest housewife blinked her eyes open and instantly knew this wasn't her parents house. This was a mansion...comparable to the one her and Tokiomi had. How did she end up her? As she stood up she noticed differences. Her hair wasn't as long for one and secondly her skin was lighter. It was then that she heard sobbing, as she walked through the mansion to try to find the source of it, maybe they'd have some answers, she passed by a mirror. In the mirror was a face she didn't know. Aoi did what most people would do, and screamed.  
***

Where.....where was this place. Saber began to stir. She was a warrior. She knew everything about her surroundings and herself, and for the first time since Merlin changed her....Arturia didn't know who she was. She was covered in a giant robe in a dark place that stunk of blood. Saber grew concerned. What...happened. Why was she like this. She looked down at her hands. Now ghostly pale and with long finger nails and bony fingers. Arturia began to panic internally...what was this....what had happened. Little did she know that in this same location a fake priest began to stir, like the others he was confused. But unlike the others, he wasn't concerned. What use was concern...when something exciting was finally happening.


	2. Chapter 2

The old man began to stir once more and he instantly felt...different. Risei Kotomine, the man who had observed and guided the Holy Grail War since the 1940s instantly felt the difference in his body. He knew what this power was. What the feeling of youth he had now regained once more was. He had become a heroic spirit. How and why....he did not know. A grin appeared on his new face, the face of the King of Heroes. While he'd find out and fix this....for now Risei Kotomine was going to enjoy his new body and his regained youth.  
***

Kariya looked in horror in the mirror. How....how could he be this....BASTARD. While he enjoyed the freedom from the pain he had experienced, Kariya hated his new face. He hated seeing him stare back. The one who had stolen away the love of his life from him. The asshole who had sent Sakura away to suffer. Of all the people he could've ended up becoming...why him. Kariya punched the wall in anger, the pain barely bothering him. He was used to pain. This didn't matter at all.  
***

Iskander, the King of Conquerors, was confused. When he had awoken, he was no longer in the house his master had made into a base. He was now in a luxurious...mansion? However Iskander quickly realized that this wasn't the weirdest thing as when he sat up, he felt it. A jiggle on his chest. Iskander looked down and saw a purple blouse covering a generous bust. Curious, Iskander raised his now dainty pale white hands, and grabbed them. The feeling of pleasure the king got from this was....unlike anything he had ever experienced before. In all of his years this pleasure was.....new. He knew that he'd have to figure this out eventually but for now... It was time for pleasure.

Iskander unbuttoned the blouse and removed it, now seeing the breasts contained in a lacy white bra. Iskander chuckled to himself in a now sing song like voice. It was then that he began to get an idea of who he was...but Iskander was so enraptured his mind quickly turned back to his current state. Iskander reached behind his new smooth back and unhooked the bra as it fell to floor. Freed from the prison, the pale white breasts jiggled as Iskander's now slim dainty fingers wrapped around them. Iskander couldn't help but moan in joy and ecstasy as he rubbed his new nipples over and over. Iskander was then distracted as he felt a wetness... The king looked down at his new skirt, now stained. A small grin emerged on Iskander's now slim beautiful face as he pulled his skirt and white panties down.

The King of Conquerors...or well potentially ex-King of Conquerors, looked down at what was now between his now shapely legs. He had seen it many times before on women, but never before had he had one himself. A saintly laugh escaped from him now as he moved his hand to his newly acquired genitalia as he rubbed it fast and furiously with one hand, while grabbing his right breast with another. What fun...oh what fun.  
***

Waver was distressed. Why had he done this again....this was a terrible idea.....he should've never done this. Now here he was, stuck in the body of Lancer...the servant of his ex-teacher's servant. How could tonight get any worse? It was then that Waver heard moans coming from a room close by....  
***

While being initially shocked after swapping with Kayneth...Sola now had better ideas. While Kayneth was still pacing and trying to think of what to do, a smug smile appeared on Sola's ((Or well, Kayneth's)) face. 

"My dear....let's go to our room." She said seductively, grabbing onto her former shoulders and beginning to lead him to their shared bedroom.

"Sola why would we-" Kayneth began to question only to be kissed quickly.

"We can fix this later, my love but for now....let's enjoy this while it lasts." Sola cooed as she pushed her body towards the bed. Kayneth gulped. While he could feel his new found nipples grow hard, and his...void grow wet...he wasn't sure. He had to fix this and get them back to their proper bodies and.....wow did he look that sexy? Kayneth was instantly distracted by his now shirtless body moving onto the bed.

"I'm shirtless now, so it's your turn." Sola said seductively, the grin still present. Kayneth nodded wordlessly and took of his shirt as Sola reached with her now beefy hands and unclipped her former bra. Her breasts now jiggled freely and she lunged at her former body kissing it passionately. Kayneth had never felt such pleasure before in his life as Sola grabbed his new breasts and moved passionately, which only increased when she rolled his pants down and then his panties while tugging down her own pants. Now they were both mostly nude, and they became united in a deeper way then they ever had been before.  
***

For the first time in ages, Kiritsugu was panicking. Here he was, now a little girl and he had no idea how or why this happened, and not just any child, but Rin Tohsaka. The daughter of one of the men he would have to kill. The Magus Killer handled this the way only he knew how. He closed off his emotions. Looking next to him, he noticed Aoi Tohsaka...the girl's mother...passed out next to him. However she was beginning to stir.

"Are you Aoi Tohsaka." He said authoritively. In his old voice it'd be intimidating and frightening. But as a little girl...it was humorous. Aoi Tohsaka looked wordlessly at the small girl giving her orders and raised an eyebrow.

"No, I am Maiya Hisau. I take it you are not Rin Tohsaka." The body of the housewife Aoi Tohsaka said seriously and humorlessly. None of the usual warmth of Aoi Tohsaka was in her reply.

"I'm not, Maiya...it's me....Kiritsugu." Kiritsugu responded, slightly blushing as he said so. For the first time in ages, Maiya Hisau gasped in shock. Of all the people...she hadn't expected that. 

"Sir how should we...handle this." She said as he looked down at her body.

"Firstly Maiya...we must get back to the mansion. I doubt Aoi Tohsaka owns a car, so we'll have to hotwire one." Kiritsugu said seriously, to an outsider a little girl speaking and looking so serious would be hilarious, but Maiya didn't laugh or smirk. She only nodded and listened. 

"And considering the age of my new...body, we're going to have to pose as our bodies' relations to each other." Kiritsugu continued. Maiya nodded wordlessly.

"Let us get moving, we must be quick. Who knows what could be occurring at the mansion..." Kiritsugu said as he worried mentally about Irisviel. He hoped that she was alright...maybe if he was lucky she'd be exempt from this. Maiya nodded and picked up Kiritsugu, now nothing more then a small child, and like the emotionless soldier she was, continued on her mission.  
***

While recovering from her shock, Aoi continued to where she had heard sobbing and found a man there. A man sobbing like.... Maybe she was wrong but...knowing what some mages could do.....

"....Rin?" She asked hesitantly. The man stopped sobbing and looked up, a smile forming on his face.

"Mother?" He said excitedly. Aoi nodded hesitantly.

"MOTHER!" He yelled and ran up to and hugged her, nearly crushing Aoi.

"I was so scared...." Rin said, her tone seeming out of place in the body she now occupied and the horrors the face she wore had seen.

"There, there..." Aoi comforted. "Everything's alright now, I'm here."

Rin nodded, the smile still on her face...only for it to fall.

"Mother I....need to go to the bathroom...how do I do it with this...thing?" She asked hesitantly and nervously. Aoi's new face fell.

**Notes for the Chapter:**

> While Iskander might possibly be out of character here, I feel like Iskander is a king who lives for pleasure and encountering something like this would be in character for him. He's not chivalrous like Saber and in history Iskander did some pretty terrible things, some of which are kept in the Fate canon.
> 
> Body swaps are-  
> Gilgamesh and Risei
> 
> Tokiomi and Kariya
> 
> Irisviel and Iskander
> 
> Diarmuid and Waver
> 
> Rin and Kiritsugu
> 
> Kayneth and Sola
> 
> Aoi and Maiya
> 
> Arturia and Gilles
> 
> Kirei and Ryuunosuke

**Author's Note:**

> Body swaps are-
> 
> Gilgamesh and Risei
> 
> Tokiomi and Kariya
> 
> Irisviel and Iskander
> 
> Diarmuid and Waver
> 
> Rin and Kiritsugu
> 
> Kayneth and Sola
> 
> Aoi and Maiya
> 
> Arturia and Gilles
> 
> Kirei and Ryuunosuke


End file.
